Ovate roadway reflector



June 3, 1952 c. H. REX 2,599,285

OVATE ROADWAY REFLECTOR Filed 001;. 6, 1948 Inventor-P: Charles H .Rex,

by mx m HIS Attowney.

l atented June 3, 1952 UNITED STATES PATENT OFFiCE OVATE ROADWAY REFLECTOR Charles H. Rex, Marblehead, Mass., assignor to General Electric Company, a corporation of New York Application October 6, 1948, Serial No. 53,120

7 Claims. (Cl. 24025) My invention relates to luminaires, and more particularly to street or roadway luminaires including reflectors.

In street or highway luminaires arranged for mounting at one side of the roadway, it is desirable that the amount of reflected light directed upon the remote side of the roadway be appreciably greater than that directed upon the adjacent side.

a side-mounted luminaire is sometimes sought to be accomplished by the use of a circular or conoidal reflector provided with one or more deflectors to redirect the light from the main reflector and lamp into two main asymmetric beams obliquely. directed up and down the roadway in opposite directions along the roadway. Each such secondary reflection, however, results in a loss of efficiency, while the use of a circular reflector further decreases the efliciency by. redirecting directly reflected light through the light source.

Accordingly, therefore, it is a general object of my invention to provide a new and improved street or roadway lighting luminaire.

It is a further object of my invention to provide a new and improved ovate reflector arranged to direct light mainly up and down the roadway in discrete asymmetric beams disposed at a high angle with respect to the vertical to the nadir.

It is still another object of my invention to provide a new and improved open ovate roadway reflector having a horizontal configuration shaped to direct reflected light around the light source The reason for this is that ob-- jects upon the roadway are discerned from a in a substantially symmetrical clearance region;

It is a still further object of my invention to vention and a further appreciation of its various objects and advantages, reference may now be had to the following detailed specification, taken in conjunction with the accompanying drawing, in which Fig. 1 is a side elevation, partially in cross-section, of a luminaire embodying my invention; Figs. 2a and 2b are identical cross-sec tional views of the luminaire reflector in the plane of the reflector rim, taken along the line 2--2 of Fig. 1, the two figures being used to illustrate diagrammatically diiferent characteristics of the reflector; Fig. 3 is a partial light distribution diagram looking vertically down upon a roadway; and Figs. 4 and 5 are vertical cross-sectional views of the reflector taken along the lines 4-4 and 5-5, respectively, of Fig. 2a.

Referring now to the drawing, the luminaire there shown by way of illustration of one embodiment of my invention, comprises an integral mounting hood and reflector casing I0 having mounted therein a socket II for a light source,

such as an elongated gaseous discharge lamp [2,

and arranged removably to support an ovate reflector l3 having a circular upper opening I30 and a lower rim portion I3b. A transparent or translucent globe l4, which may suitably be formed of diffusing glass, is removably connected to the rim of the casing [0 by bolts I la and brackets Mb. The discharge lamp I2 is vertically mounted and so positioned that its effective light center is located slightly above the plane of the reflector rim and on a vertical line passing through the intersection of the major and minor reflector axes in the plane of the rim. It will of course be understood that, if desired, an incan the plane through the major axis l5 and perpendicular to the plane of the rim. As further 'explained below, the reflector I 3 is particularly designed for disposition at one side of a roadway with the plane of symmetry. disposed perpendicularly across the roadway and at right angles to the roadway surface.

In the embodiment of the invention shown in the drawings the efiective light center s is shown 2,599,286 r v r coincident with the point of intersection of the major and minor reflector axes in the horizontal plane through the light center s. If desired, and indeed by preference, the effective light center s is slightly eccentric and is positioned on the major axis slightly to the rear of the point of intersection of the axes. In Fig. 1, such positioning can be accomplished by mounting the reflector 13 with its circular upper opening i311 eccentric with respect to the lamp I2. Such eccentric positioning puts a greater amount of light on the roadway surface.

The ovate shape of the reflector i3 is illustrated by its cross-sectional configuration in, the plane of the rim as shown atFig. 2a} Eronithie figure, it is evident that the reflector is only slightly ovate, and to this end, the length ratio of the minor axis it to the'major ax-is [5 in the plane of the rim is at least 4/5. The ovate shape is further characterized by the fact that cords l1 and I8 taken at equal predetermined distances a from the minor axis H5 and parallel hereti a e of unequal n th/ h eehi H therear or house side of the reflector being somewhat shorter than the cord 1,8 onthe front side of the reflector.

Thecross-sectional configuration of the reflecer n, t e. f of the im eh n l e arall l thereto is decreasingly ovate from the rim towardthecircular upper opening 3a. This ovate p is designed to accomplish two principal f1 ctionjs; first; to define two discrete main be of light'directed asymmetrically up and d 'n the roadway in oppositedirections; and second, to' direct light reflected from substantial.- l'y all points horizontally around the reflector thr-Qugh a clearance region radially spaced away from a vertical line passing thPQQQh. the effech i h ce r 2 l tra es e manifi hwhich both these desirable functions are ac omplished. Usually the clearariee region ie ou ide the lamp e v l Wh a aseou d k ha e'el am is. sed, b t en an. ea ele pe lamp? s use h c ea a c e ion a pass through the glass bulb, itbeing sufiicient that the incandescent filament is space'd from the clear: ahee. region.

Referring now more particularly to the sectipnalviewFig. 2b, it will be noted that the re fie tor illustrated is symmetrical on oppqsite idesc he. major, plane.- ac 'r ar uadrant of the reflector includes a portion l9. whieh is parabolic in horizontal cross-section and has its fee at f, the point of intersection of the major an minor reflector axes'in the plane of the secti The parabolic portion 19, may suitably tend an angle of about, 2,4 de e s nd ave.

t axied s d at n an e or beut 60 eg ee wi hthe major axis l5, as shown. This parabolic portion of the rear quadrant therefore projects a discrete beam of parallel light rays between the lines marked 60. The corref ondmg parabolic portion of the other rear quadrant projects a similar beam of parallel rays: in'the opposite direction along the roadway.

Apart from the parabolic portions 19, the

cross-sectional configuration of the reflector in the plane'of the rimis a composite curve formed o'fa plurality of adjacent elliptical pertions, each i wfhieh ha a rim ry f sa f and a en er focus lying in an annular clearance area c which is radially spaced from the primary focus I. The reflection 'of light from elliptical portions of the rear quadrant at two points I59; and labon opi sidee ef h ar b he q fti h it e indi cated by the lines marked 45 and 80 respectively, at Fig. 2b. These two points are chosen to subtend an angle of 58 degrees of direct light from the center of the source at f, with one such point on the minor axis 16 and the portion i9 approximately centrally between the points. It will be noted that all the light falling on th s. r ie 9 ar. uadra t d y from the source'and within thefarc of258 degrees is redirected into a reflected beam'subtending an angle of only degrees with the source as a center, i. e., between degrees and 8'0 degrees, measured from the primary focus I. Thus, a large, amount, ef light is collected in the rear quadrant and reflected into a relatively narrow beam generally along the line from the parallel beam from the parabolic portion 19. The result is that an intense. main beam of reflected light isdirected obliquely up the roadway in one direction. A similar intense beam is collected through a 58 degree angle or other suitable collecting angle, of the other rear quadrant and directed obliquely down the roadway in the opposite di rection. The secondary foci offthe lighti'rays reflectedfrom the points 19a; and 19b of the rear quadrant are shownat' f1 and fi respectively :1";

Fig. 22). These foci lie in the clearance area c.

Additional representative reflectedr'ays 2 0 and Zila from a front quadrant of the reflector are shown in broken lines atFi'g. 2b. As 'prev'icuay" stated, the front quadrantsof t he reflector are formed of a plurality of adjacent elliptical'sec tions, each having their primary focus atf and secondary foci inthe clearanceiarea c, The 'r ondary foci of the ellipticalv sections fromwhich the reflected rays 20 andzfld are directed'are in Figs. 2a and 2b, is taken in theplane of the shown at Fig. 22) at is and f4, respectively: both' ofwhichliein the clearance area a,

Thehorizontal cross-sectional configuration of the reflector l3, described above and'illustrated e o r m. 13b- A e e he ehe the .e-. fiecto'r rim, the hor'iaontal section'sof the reflector in planes parallel toi the. plane of theriin, c m e he y ev te! e rree'ehine e ar le e in t th e f the eeteh The n e i te ete se i s ar sim r all res ectsto those shown atFig's'. Zia/and 215. e t hat e ehs't retiq 9f he ino to the; a o is wh pre erabl etlee t 4/ at he plane of he m; e ee ngly p r a h s. ni y et p r efl t r o en n ts, twill e" i h h t wi hthe m io axis. apn eeeh he the minor axis in length in successive'horizontal ane oach n e on there iee ri fi e( m e adius he lea an e are, e creases as the tene the re leeter ief hroeehed. until na a the reulair e t on atth p; efle ted ra s pass hrough he nte se tion O e axe Th he eer he e i n h' ree: dimensional View, conical in shape with its, pe at the tenet the ef e te The c ss eeeti'e ei herefleeter l3. lan rm lly. ve c an merejpa ieh er v an lanes. pe endicular q. the? plane he th ef.

t e. e ee er a he udin ht ra efleet d' frorn'that poi t f thelr eeter whe e the ec on s k n s em es flte ve. hav n ie ar'eb l tion in e we z e die eh he e l e er m Bhe en e ptiee Po tion ex ehq 'f e'm he ow r e t h u er fiee e peh h I311- Fig; 5 shows thevertical cross sectio'n a: the ree el he he ne e 5 E118.- ieh F shows the vertical cross-section'fof therefiectgr eral, the vertical cross-sections of the reflector in planes including light reflected from the sections are so shaped that light reflected from each section will be redirected at the highest desirable angle without impinging upon the lower edge of tions in vertical cross-section are-indicated by brackets adjacent the various diagrams.

The cross-section shown at Fig. 5 is taken through that portion l9 of the reflector which is parabolic in horizontal cross-section, and the parabolic lower zone at this section has its 150- cus at the effective center 3 of the light source and its axis disposed at a relatively high angle from the vertical to the nadir. By way of illustration, I have shown an angle of 74 degrees between the axis of the parabolic portion 20 of Fig.

5 and the vertical to the nadir. The upper zone 2| of the reflector in the section at Fig. 5 is elliptical in configuration and has its primary focus at f and its secondary focus at is, slightly below the rim of the reflector on the opposite side of the major axis. It will, of course, be understood that an intermediate portion of the other rear quadrant corresponding to the portion I9, is similar in vertical cross-section to the section at Fig. 5, the parabolic axis of the lower zone being high relative to its inclination at other points around the reflector rim.

The vertical cross-sectional view shown at Fig. 4 is taken on either side of the parabolic horizontal portion IQ of Fig. 2b. That is, the vertical cross-sectional view of Fig. 4 is taken at a point on the rim periphery which is of elliptical configuration in horizontal section. The sectional view shown at Fig. 4 is similar to that shown at Fig. 5, except that the lower parabolic zone 22 at Fig. 4 has its axis disposed at a slightly less angle with respect to the vertical'to the nadir. By way of example, I have shown an angle of '72 degrees between the parabolic axis and the vertical, as compared with 74 degrees at Fig. 5. The upper zone of the vertical cross-sectional View of Fig. 4, indicated at 23 on the drawing, is elliptical in cross-section, having its primary focus at f and its secondary focus at is,

slightly below the reflector rim on the opposite side of the major axis. The remaining vertical cross-sections around the reflector are similar to that of Fig. 4, except in the opposite rear quadrant portion corresponding to the portion l9.

It will now be understood that the lower zone of the reflector, which is parabolic in vertical cross-section, casts a generally conical beam of reflected light at high angles passing immediately below the reflector rim, but that those intermediate portions IQ of each rear quadrant of the reflector which are parabolic in horizontal cross-section, direct light at slightly higher angles, that is, at a lesser inclination to the plane of the rim than do any of the other vertically parabolic portions around the periphery of the reflector. This means, of course, that the parabolic portion of the main beam cast by the horizontally parabolic portion IQ of each rear quadrant, and indicated between the 60 lines at Fig. 2b, is thrown out at an angle slightly higher above the vertical to the nadir than is light reflected from the lower reflector zones at any other portions around the periphery of the reflector The distribution of reflected light into two main asymmetric beams is indicated at Fig. 3, in which I have shown a plan view of a roadway including a partial light distribution diagram for one of the main reflected beams. At Fig. 3, I have shown the roadway pattern formed by the main beams of reflected light from that rear quadrant portion of the reflector shown at Fig.

' 2b as subtending 58 degrees of directly projected light. As previously pointed out, the central portion of this beam is formed of parallel rays directed at 60 degrees measured from the major axis in the plane of the rim, and is indicated by the line 24 of Fig. 3. This beam of parallel rays forms an angle of 74 degrees with the vertical to the nadir, as shown at Fig. 5. Likewise, as previously indicated, the main reflected beam is concentrated in an angle of 35 degrees measured in the plane of the rim, one of its limits being at degrees with respect to the major axis and the other limit at 45 degrees with respect to the major axis measured in the plane of the rim, as indicated by the lines 25 and 2B of Fig. 3, respectively. The rays 25 and 26 are directed at vertical angles of '72 degrees with respect to the vertical of the nadir, as indicated at Fig. 4.

The foregoing description of the light distribution by a reflector embodying my invention has been based upon the assumption that the reflecting surface is specular in nature. It is possible, without disturbing greatly the general plan of light distribution, to etch the inner surface of the reflector lightly and thereby to reduce the maximum candle power and provide some additional diifused light. It will be appreciated that a certain amount of diffusely reflected light may be desirable at the outer periphery of the roadway pattern.

While I have described and illustrated a preferred embodiment of my invention in which the reflector is symmetrical on opposite sides of the major plane, I wish to have it understood that without departing from the scope of the invention, the reflector may, if desired, be soshaped that the main lateral beams directed along the roadway in opposite directions are at different angles with respect to the roadway center line.

Throughout the foregoing specification as well as in the following claims, I have referred to my reflector as an open reflector, and I have referred also to vertical and horizontal sections. By the use of the term open, I do not intend to exclude from the scope of my invention reflectors of the type described when used with enclosing glassware, and indeed, I have illustrated such glassware at Fig. 1 of the drawing. By the term open reflector" in the specification and claims, I mean merely that the reflector is shaped to function without the aid of refracting glassware, as distinguished from simple enclosing glassware. If, of course, further redistribution of light from my reflector is desired, such redistribution may be accomplished by the use of prismatic refracting glassware within the scope of my invention. Similarly, the terms vertical and horizontal have been used for simplification of description, it being assumed that the reflector is normally positioned with the plane of its rim horizontal. It will, of course, be understood that, if desired, the reflector may be. mounted with. the plane of the rim slightly 7 obliqueto the roadway. Thus, the wordswer'tical and horizontal are to be understood as defining only perpendicularity and parallelism,respectively, with the plane of the reflector rim.

While I have described only a preferred embodiment of my invention by way of illustration, many modiflcations'will 'occur to'those skilled'in the art and I, therefore, wish to have it understood :that I intendin the appended claims to cover all such modifications as fall within the true spirit and'scope of my invention.

What I claim asnew and desire to secure by Letters'Patent of the United States is:

l.-A roadway luminaire comprising an open ovate reflector arranged for mounting at one side ofaroadway with its major plane disposed perpendicularly across said roadway, the plane of the rim 01 said reflector'being perpendicular to said major plane and'including minor and major reflectoraxes having a length ratio of at least 4/5, :the cross-sectional configuration of said reflector in the plane of said rim being a composite curve comprising a parabolic portion in each rear quadrant anda plurality of adjacent ellipticalportions having their primary foci at the point of intersection of said major and minor axesand their secondary fooi lying in anannularclearance area radially spaced from-said point oflint-ei'section.

2. 'A roadway luminaire comprising-an open ovate'reflector arranged for mounting at one side ofa roadway with its major plane disposed perpendicularly across s'aid roadway, the plane of the rim of said reflector being perpendicular to said major plane and includin minor and major reflector axes having a length ratio of at least 4/5, the cross-sectional configuration of said reflector in the plane of said rim being a com posite curve comprising a parabolic portion interme'diately position in each rear quadrant and a plurality of adjacent elliptical portions having their primary foci at the point of intersection of said major and minor axesand their secondary foci lying in an annular clearance area radially spaced from said point of intersection, thereby to define a pair of discrete main beams directed asymmetrically up and down said roadway in opposite directions.

3. Aroadway luminaire comprising an open ovate reflector having a plane of symmetry and arranged for mounting at one side of a roadway with said plane oisymmetry. disposed perpendicularly across said roadway, the plane of the rim of said reflector beingperpendicular to said plane of symmetry and including minor and 'major reflector axes having a length ratio of at least 4/5, the cross-sectional configuration of said reflector-in the plane of said rim being a composite curve comprising a parabolic portion intermediately positioned in each rear quadrant and a plurality of adjacent elliptical portions having their primary foci at the point of intersectionof said major and minor axes and their secondary focilying in an annular clearance area radially spaced from said'point of intersection, and means for mounting within said reflector a light source having'its effective center above the plane of said rim and lying substantially on the vertical tothe nadir through the point of intersection of said minor and major axes, the cross-sectional configuration of said reflector in substantially all planes perpendicular to the plane of said rim and including light rays reflected directly from each point-on the periphery of said rim being parabolic in a lo'wer zone adjacent said rim and elliptical 8 in. an upper zone extending substantially to the top ofsaid reflector.

-4. A roadway luminaire comprising an open ovate reflector having a major plane-of symmetry and arranged formounting at one side oi a. roadway with said major plane disposed'perpendicularly across said roadway, said reflector having a rim lying in a plane perpendicular to said major plane and having minor and major axes in' planes parallel to the plane of said rim whose length ratios are at least 4/5 inthe'pl'ane of said rim and increasingly approach unity at thetop of said reflector,1thecross-sectional configuration of said reflector in those of said parallel planes'in which said axes are of unequal length'being composite curves includuinga plurality of adjacent elliptical sections having their primary tool on a center line passing through the points of intersection of said major and minor axes and secondary Lfoci lying in a conical clearance regionradially spaced from said center line.

5. A roadway 'luminaire comprising an open ovate reflector having a plane of symmetry-and arranged'for mounting at one side of aroadway with said plane of symmetry disposed perpendicularly acrosssaid roadway, said reflector having a rim lying in a plane perpendicular to' said plane of symmetry and having minor'and major axes in planes parallel to the'plane of said rim whose length ratios are at least 4/5in the plane of said rim and increasingly approach'unity at the top of said reflector, the cross sectional configuration of'said reflector in those of said parallelplanes in which said axes are unequal in length bein composite curves including a parabolic-section intermediate the ends of each rear quadrant and a plurality of adjacent elliptical sections having their primary foci on a center 'line passing through the points of intersection of said major and minor axes and secondary foci lying in'a conical clearance region radially spaced from said center line.

6. A roadway luminaire' comprisingan-open ovate reflector having a major plane and a rim lying in a plane perpendicular to said major plane, said reflector being arranged for mounting with said major plane disposed perpendicularly across said roadway, the cross-section of said reflector in the plane of said rimhaving minor and'major axes whose length ratio is at least 4/5 and comprising a parabolic portion-in each rear quadrant and a plurality-of elliptical portions having their primary ioci at the point of intersection of said minor and major axes and their secondary foci lying in an annular clearance .area radially spaced from said point of intersection, and means formounting within said reflector a light source having an effective center lying substantially on the vertical to the nadir through said point of intersection, the cross-sectionalconfiguration of said reflector in substantially all the planes perpendicular to the plane of said rim and-including light rays reficcted directly from each point on said rim being parabolic in a lower zone adjacent said rim, the axes of said parabolas being'less inclinedto the plane of said rim at said parabolic portions of the periphery of said ri-mthan elsewhereon said periphery, thereby to define a pair of main asymmetric beams oppositely directed up and down'said roadway.

7. A roadway luminaire comprising an open ovate reflector having a plane of symmetry and a rim lying in a'plane perpendicular'to said plane of symmetry, said reflectorbeing arranged for mounting with said plane of symmetry disposed perpendicularly across said roadway and having minor and major axes in planes parallel to the plane of said rim whose length ratios are at least 4/5 in the plane of said rim and increasingly approach unity at the top of said reflector, the cross-sectional configuration of said reflector in those of said parallel planes in which said axes are of unequal length being composite curves including a parabolic portion in each rear quadrant and a plurality of elliptical portions having their primary 001 on a center line passing through the points of intersection of said minor and major axes and their secondary foci lying in a conical clearance region radially spaced from said center line, and means for mounting within said reflector a light source having an effective center lying substantially on said center line. the cross-sectional configuration of said reflector in substantially all the planes perpendicular to the plane of said rim and including light rays reflected directly from each point on said rim being parabolic in a lower zone adjacent said 10 rim and elliptical in an upper zone, the axes of said parabolas being less inclined to the plane of said rim at said parabolic portions of the periphery of said rim than elsewhere on said periphery, thereby to define a pair of main asymmetric beams oppositely directed up and down said roadway.

CHARLES H. REX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

